As doctors and scientists race to understand the many ways in which COVID-19 ― the illness caused by the novel coronavirus ― affects the brain and body, they’re also trying to figure out the sort of long-term impact the infection could have on patients.

The virus has only been around since late December, or at least that’s what the current evidence suggests, so even the initial COVID-19 patients are still in their early days of recovery.

A new study from China gives us a first glimpse of what may be in store for patients who battle moderate-to-severe cases of COVID-19. By testing biological markers of recovered patients, researchers found that recovered patients had lingering issues with liver function. The intense damage we’re seeing in some people’s lungs and hearts also has researchers concerned that the health issues won’t end once the infection clears up.

It’ll take years before we have a clear understanding of how COVID-19 impacts people’s health in the long run, but here’s what health experts think we might see.

COVID-19 can trigger a lot of inflammation, which can lead to organ damage

To understand the impact COVID-19 may have on the body, it’s crucial to first take a look at the immediate damage the disease inflicts.

When the body is exposed to an infection like COVID-19, it mounts an inflammatory response, in which the immune system pumps out cells to fight the virus. With COVID-19, some people’s bodies are producing way too much of an inflammatory response that’s harming critical organs like the lungs, kidneys, and heart, according to Khalilah Gates, a pulmonologist and assistant professor of pulmonary, critical care and medical education at Northwestern University’s Feinberg School of Medicine.

The body cannot recover from that level of damage overnight, and it must heal itself. “Unfortunately, particularly in the lung, this healing process can lead to irreversible scarring (fibrosis) that can greatly impact lung function long term,” Gates said. This loss of lung capacity could involve anything from shortness of breath to a long-term need for oxygen.

COVID-19 is also putting extreme stress on people’s hearts. Harvard University specialists called it “one big stress test for the heart,” stating that the inflammation and high fevers brought on by the coronavirus weaken the heart and increase the risk for cardiac abnormalities like blood clotting.

Len Horovitz, an internist and pulmonary specialist at Lenox Hill Hospital in New York, expects that some people who battled a severe bout of COVID-19 may go on to develop heart arrhythmias, congestive heart failure and myocarditis or pericarditis (inflammation of the heart muscle).

It matters how severe someone’s bout with the illness is. Those with milder symptoms may be less likely to run into COVID-related health issues down the road — it’s the more severe cases that have experts worried. If you have a mild case, “you’re not going to have any scarring or breathing issues long-term,” Horovitz said.

In general, health experts predict that the less inflammation a patient experiences, the less long-term effects they’ll have.

SARS and MERS both led to lung scarring

Other respiratory infections that were slightly similar to COVID-19, like SARS and MERS, are known to have lasting health consequences.

One complication being seen with COVID-19 is a form of respiratory failure called acute respiratory distress syndrome (ARDS), which requires patients to receive oxygen via a ventilator.

ARDS isn’t triggered by COVID-19 alone. It’s also caused by other infections like sepsis, influenza, and pneumonia. Past studies suggest it can diminish people’s quality of life and bring on exercise limitations and neuropsychological disorders, even after they’ve recovered.

“We know from influenza and ARDS and other causes of ARDS that, based on the severity of the acute illness, there can definitely be long-term consequences from the inflammation and scarring,” said Gates. She added that this can lead to “irreversible lung damage and lung impairment that can lead to chronic respiratory symptoms and need for oxygen long-term.”

A study from Beijing looking at the health of recovered SARS patients after 15 years found that about a third of patients had lung issues for a few years following their infection, but the pulmonary damage mostly cleared up by the 15-year mark.

A similar discovery was noted with MERS: During follow-up appointments, about a third of recovered patients had signs of fibrosis, or scarring of the lungs.

“There is clearly an incidence of scarring from SARS,” Horovitz said, adding that scarring is linked to a loss of lung capacity.

Much of the time, these pulmonary issues do seem to improve with time, typically within a few years.

“We may see more lung function impairments, although based on prior research we know that those usually improve over the subsequent months and years,” said Lauren Ferrante, a pulmonary and critical care medicine physician and an assistant professor the Yale School of Medicine.

Still, this is based on what is known about similar illnesses; not enough data is available to determine if that will be the case for COVID-19.

People may have impaired mobility

One thing Ferrante is sure will be seen with many patients with a severe case of COVID-19 is a battle with cognitive and physical function in the weeks and months after leaving the hospital.

This is commonly observed with patients admitted to intensive care units for other reasons. Bed rest can take a serious toll on the body; people can experience muscle breakdown quickly when they’re stuck in a bed in the hospital. A Johns Hopkins University study found that for each day a person was on bed rest, their muscle strength dropped from 3% to 11% over the following months and years.

Ferrante is concerned these problems may be magnified after COVID-19. The treatment recovery programs in hospitals usually used to help patients get mobile again are not being delivered. And on top of that, it takes coronavirus patients a long time to recover — usually about two weeks.

“That’s more time that these patients are spending in bed, not moving, stuck on a ventilator,” Ferrante said.

She is concerned many COVID-19 patients, particularly those who are older and frail, will have trouble with physical function.

We won’t fully know the consequences for years

Gates said it will take months to years to fully understand the impact long-term health effects of COVID-19

Researchers will need to follow patients over time, and look for changes and in their hearts and lungs and other key organs, to see if the damage is long-lasting or if the body is able to make a swift recovery.

“I like to tell my patients recovering from other infections, even when you’re discharged and you’re feeling better, your body is still healing,” Gates said. “Healing and recovery take time.”

Experts are still learning about the novel coronavirus. The information in this story is what was known or available as of press time, but its guidance concerning COVID-19 could change as scientists discover more about the virus.